Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Goes well beyond the annotations (readOnlyHint, openWorldHint=false, destructiveHint=false) by disclosing the access model ('Reads only the material in the call ... no money movement'), the cost and free tier (0.10 USDC per call on Base via x402 exact, 10 signed-wallet free calls per rolling 30 days), the required X-Wever-Wallet-Proof binding to the JSON arguments and route, and that the response carries an Ed25519 signed receipt.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loaded with what the tool takes and returns before the payment and contract details, and nearly every sentence carries operational information. The opening sentence is long and clause-heavy, and the trailing contract/human-page URLs are lower value for an agent, so it is efficient but not maximally tight.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

There is no output schema, but the description fully specifies the return: a per-rail fits / fits_with_caveats / does_not_fit verdict with itemized deciding facts, computed fees, a named best rail, an overall rail_fits / fits_with_caveats / no_rail_fits verdict, and a signed receipt. For a nested, paid, read-only evaluation tool, nothing material is left for the agent to guess.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 75%, so the schema already carries much of the meaning, but the description adds real semantic value by enumerating the expected rail fields (name, networks or currencies, fee shape, min/max amounts, settlement time, stated limits) and requirement fields (amount, currency, destination type, network, deadline). It also explains that fees are computed 'from its stated shape', which is more than the nested schema states.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a concrete verb and resource: submit two or more payment rail options plus one requirement and get a fit verdict per rail with the best rail named. It also scopes itself explicitly ('Supplied options only') and explicitly disclaims wallet/chain/market/bank lookups and money movement, which separates it from execution-oriented siblings such as wever_payout-execute or wever_unified-agent-checkout.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

It defines the input shape ('two or more rail options ... and one payment requirement') and the exclusion 'Supplied options only', which tells the agent when not to use it (when rail data must be discovered first). It does not name a specific alternative sibling tool to use instead, so the routing hint is implicit rather than an explicit when/when-not/alternative triad.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.